(1) Field of the Invention
The present invention relates generally to a computerized manufacturing system and, in particular, to a new and novel method for controlling the production, including pricing, costing, scheduling etc., by such a system.
(2) Description of the Prior Art
Material Requirements Planning (MRP) is the technique for determining the net time phased requirement of dependent items parts or sub-assemblies from known (e.g. sales orders) or assumed (e.g. sales forecast) independent demand. A Bill of Materials (BOM) is used to define a relationship between the independent demand items at one level and the dependent demand items at the next lower level. In addition, the BOM also is used as the basis for costing and pulling materials from inventory for released work orders. Typically MRP planning is carried out by a general purpose computer operating under software control.
In most prior art MRP systems, there is an "one-for-one" relationship between an independent demand item produced and the BOM which defines the dependent items and the quantity of each dependent item required to build the independent demand item. Some MRP systems have the additional capability of including limited conditions in the BOM. However, such MRP systems do not include any general provision for providing a "many-to-one" relationship between the independent demand items and the BOM.
Unfortunately such MRP systems pose a problem for an user which manufactures and sells products that are available in a wide variety of options. Upholstered furniture companies, for example, sell chairs by style number. They are often available in a variety of fabrics and finishes. Another example is found in the apparel industry where it is common to specify product by style, size and color.
The general MRP solution for this type of manufacturer is to enter into its MRP system a product number and a BOM for each possible style/option combination. While this approach is conceivable, it would necessitate thousands of unnecessary product numbers and BOMs. This would create a huge problem in maintaining the BOMs and entering the data into the MRP system. As a result, there now are a number of industry specific MRP systems which allow, for example, a furniture manufacturer to enter individual styles, fabrics and finishes which correspond to specific sub-BOMs, thereby substantially reducing the total number of BOMs required to be maintained and entered into the MRP system.
Certain disadvantages become apparent for such a MRP system. First, these MRP systems are specific solutions rather than general purpose. Thus, they can not be readily adapted for different industries or even different manufacturers in the same industry. Furthermore, a manufacturer can not add or easily modify his product structure. For example, adding the option of a sectional sofa for an existing style (i.e. add another "degree of freedom").
There have been some attempts at otherwise simplifying, limiting the data entry into the MRP system, and increasing the reliability of production estimates of the MRP system. For example, the Dye patent (U.S. Pat. No. 4,459,663) discloses a data processing system for automatically and efficiently controlling the manufacture of designated end item products and components which are used to make them. The MRP system is a basic MRP system which, in addition, incorporates an unique feature whereby the system automatically maps all end item stock to the jobs on a priority basis every time a MRP report is produced. As a result, it is not necessary to continually update the MRP system with changes made to the original stock allocation as required in prior art approaches.
The Carlson et al reference (U.S. Pat. No. 4,646,238) discloses a MRP system for controlling the flow of semiconductor products and their components through a production facility. In addition to a conventional MRP system, the Carlson patent also provides a method for by-product planning, co-product planning, and downgrading. However, neither of these references provides a solution to the problem of problem in maintaining the BOMs and entering the data into the MRP system for a distributor or manufacturer which sells products that are available in a wide variety of options.
It has thus become desirable to develop a MRP system which allows, for example, a furniture manufacturer to establish an one-to-one relationship between a style number and its BOM without regard to selected fabrics or finishes and, in addition, allows the manufacture to utilize user-defined formulas which determine the quantity and/or size of an item based on the selected options, thereby eliminating the extra number of BOMs required to be maintained and entered into the MRP system.